الفهرس 
Investigation on physical properties of Li1.1Co0.3Fe2.1O4 spinel ferrite nanoparticles
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Abstract
Due to their technological applications, nanocrystalline ferrites, especially spinel
nanomaterials, have evoked greater interest in this decade. The investigation of the
properties of doped nano ferrites helps to improve their performance and make their
applications more diverse. The demand for high-performance devices is an important step
towards synthesizing the investigated samples in nanoscale form. The lithium cobalt spinel
ferrite with the general formula Li1.1Co0.3Fe2.1O4 is a low-cost material which is generally
useful for numerous applications.
In the present study, we have synthesized the Li1.1Co0.3Fe2.1O4 ferrite nanoparticles
by using the citrate auto combustion method.
The distribution of cations on A-site and B-site is studied by X-ray diffraction
(XRD), High-Resolution Transmission Electron Microscopy (HRTEM), Field emissionscanning electron microscope (FESEM), Atomic force microscopy (AFM), and Raman
Spectroscopy. In addition, X-ray photoelectron spectroscopy (XPS) is carried out to
identify the various ions existing in samples and their oxidation states. The XRD study
confirms that prepared nanoparticles are cubic spinel structures having an Fd3m space
group and the crystallite size is approximately 36 nm.
The magnetic hysteresis loop has been studied by the Vibrating Sample
Magnetometer. The samples have less magnetization because the magnetization of the Asublattice becomes much diluted, and the A-B exchange interactions become weaker or
comparable to the B-B exchange interactions. Consequently, the canted spins and the
Yafet–Kittel (Y–K) angle are increased. Additionally, it can also be owed to the formation
of an inactive magnetic layer and the disordered cation distribution.
VII
The electrical conductivity as well as the dielectric constant were recorded as a
function of frequency and temperature.
The resistivity mechanism of humidity sensors is studied via complex impedance
spectroscopy (CIS). Its impedance data is fitted to a corresponding circuit to achieve a
simulation of the sample under study. This fitting is detected by the Nyquist plot (ColeCole). The obtained data confirms that the studied samples are very sensitive to humidity
and can be commercially used as a humidity sensing element.
The Li1.1Co0.3Fe2.1O4 has also been employed as a sorbent material for the removal
of lead (II) ions from wastewater. Two models of adsorption isotherms (Freundlich and
Langmuir) are utilized to recognize the adsorption mechanism.
Finally, this work is focused on some of the critical issues of investigating
nanoparticles as active materials in Li-ion batteries, namely, electrode preparation,
nanoparticle synthesis, and electrochemical characterization. The cyclic stability was
scrutinized via galvanostatic charging/discharging (GCD) and electrochemical impedance
spectroscopy (EIS). Its purpose is to act as a reference for future work in this area.